Help With Routine Maintenance On J30

[CustomJ30]

I Have A 1995 J30 With 142K.....Recently One Of My Belts Has Been Squealing But It Was Only When The Car Started, Now There Is A Very Low Squeal As I Drive Always, Also Im Thinking Of Having The Spark Plugs Changed(OEM Nissan Correct?), And My AC Blows Cool For About 30 Minutes Then After That It Just Blows Air(Not Warm But Not Cold Either) And Living In Miami My AC Is Needed.....Is There Anything Else I Should Have Done To My Car? Any Suggestions Are Appreciated

[RPS13 Rocket]

Spark Plugs = NGK ONLY (don't spend the extra money at the dealership, NGK are what they will give you anyways)

Belts are an easy thing to diagnose if you know what you are looking/listening for. Take a bar of soap and hold it against the ribbed side of the each belt individually with the car running. By doing them one at a time you will be able to eliminate each belt until you find the one that is squealing, as it will stop squealing almost immediately as you apply the soap. Then just find out what belt it is and replace it. It could however be the accessory that it is turning causing it to squeal so keep that in mind when replacing the belt as you might be replacing the accessory too.